Strings Contain Empty Strings

This is just one of those philosophical moments in programming where one small details can have a big impact. In C# / .NET you will find that when you ask if a string contains an empty string (string.Empty), the answer is yes. This may seem logically surprising so it is worth bearing in mind should you be comparing strings.

// True
bool isMatch = "some string".Contains(string.Empty);

A more realistic example is below, imagine you have a config file with some value, and the value isn’t set for some environment… every comparison made will match.

private string GetItem(string item) {
  // True
  bool isMatch = item.Contains(_config.RudeWord);

  return isMatch ? string.Empty : item;
}